Known preassembled drainage line units constitute loose aggregate in the form of lightweight materials, such as polystyrene beads provided in surrounding relationship to a preferably perforated conduit and bound thereto by a perforated sleeve member, such as plastic netting. Known units may or may not comprise the perforated conduit, or pipe, to be completely effective in a selected use, as explained more fully in commonly owned U.S. Pat. No. 6,854,924 (See Col. 1, lines 15-31).
While known preassembled drainage line units have enjoyed commercial success, certain potential performance limitations persist with respect to manufacture and application. For example, depending upon the type of fill placed over the preassembled units, solids, such as sand or dirt may pass, and otherwise infiltrate downward through the exterior cover, such as the plastic or other sleeve binding netting, and into the void areas between adjacent aggregate used to fill the netting sleeve. Such infiltration can clog these adjacent areas and cause an undesirable reduction in fluid flow through the aggregate. In other applications, it is desirable that the preassembled units, which are normally flexible along their length possess greater rigidity along their length. In still other applications it is desirable or beneficial to provide structure as part of such units to promote the growth of microorganisms within the drainage units.
Commonly owned U.S. Pat. No. 6,854,924 discloses the use of a barrier material incorporated into the preassembled unit in an attempt to solve some of the enumerated shortcomings of prior, known devices. As stated above, the '924 patent is incorporated by reference in its entirety as if made part of the present application.
The improved products of the present invention as described below have been developed to overcome the problems associated with the units described in the known prior art and to better fulfill market needs.